(42g) The Contribution of Different Surfactants within Corexit in Ejection of Oil/Dispersant Material to the Atmosphere

Paria Avij, He Huang, Zenghui Zhang, Francisco R. Hung, Kalliat T. Valsaraj

Cain Department of Chemical Engineering, Louisiana State University

The Deepwater Horizon (DWH) oil spill was one of the largest marine oil spills in U.S. history, during which vast quantities of crude oil were released into the sea-surface environment of the Gulf of Mexico. Ample research has been focused on the transportation of oil into the different environmental sections which includes air, water, sediment, and biota. Nevertheless, the only considered transportation pathway of oil spill matter into atmosphere has been evaporation. In our work, we study the aerosolization of oil and dispersant matter by whitecaps, which are simulated by bursting bubbles in a laboratory aerosolization reactor. The reactor incorporates an annular shear sparger which produces abundant, small sized bubbles.

In our experiments, different organic material including oil, mixtures of oil and Corexit (dispersant), and mixtures of oil and surfactants (DOSS, Tween 80, Tween85, Span 80) have been injected into the reactor. Since the reactor is capable of simulating both evaporation and surface adsorption transport processes, we collect the gas and particle phases at the reactor effluent and analyze these phases by GC-MS/GC-FID and LC-MS-MS for their alkane and surfactant content. We have clearly shown the air-water interface driven ejection of oil/dispersant material to the atmosphere via bursting bubbles.

Moreover, our experiments show that the ejection of oil matter via bursting bubbles occurs both in the presence and the absence of Corexit and this ejection is enhanced (especially C20-C30) when a dispersant is present. Also, through experiments of mixtures of oil and the individual components (surfactants) of Corexit, different ejection rates and dispersion behavior of oil matter were observed. Investigation and knowledge of these experiments will help us to have a better understanding about the surfactant behavior when they are exposed to the oil at the air-water interface. Likewise, this will help us implement possible corrections to the current dispersant formulation, which includes a lower ejection of oil matter into the atmosphere and a higher dispersion level within the water column.